Purpose: To modify the technique of Sofield to minimize avascularity and to maximize stability. Introduction: Sofield and Millar described a technique for the correction of severe long bone deformity in osteogenesis imperfecta which involved removing the diaphysis from the limb and cutting it into several segments. These segments were then threaded on a rod without regard to their original position in the bone, their end to end orientation, or their rotation. The patient was then immobilized in a plaster cast. In order to avoid the extreme bone atrophy seen in some patients, sometimes called ‘disappearing bone disease’, and to provide sufficient stability to obviate cast immobilization we have modified Sofield’s technique. Surgical principles: Our technique follows the following guidelines: 1. Make as few osteotomies as possible; 2. Avoid, if possible, completely stripping any segment of bone; 3. In severely angulated bones which cannot be made straight without shortening, the part of the bone excised should include the area of maximum deformity; 4. In order to maximize angular stability make the cuts as far from the ends of the bone as possible; and 5. In order to achieve rotational stability make the cuts 45 degrees oblique. Material and methods: We reviewed 46 bones of 23 patients aged 1 to 20 years at the time of the study. There were 23 tibiae and 23 femora. We measured the angular deformity of the mechanical axis of the distal femur and the proximal and distal tibia. Six patients had only one bone corrected, 9 had two, 4 had 3, and 2 patients had corrections of both tibiae and both femora. We counted the number of cuts on the post-operative x-ray. Achieving shortening by removal of a piece was counted as one cut since it did not produce an additional segment. We noted whether or not a post-operative cast was used. Results: In no case, not even in the most severe deformities, were more than two cuts required. There was no difference in the tendency of the femur and tibia to require more than one cut. We observed no instances of ‘disappearing bone disease’. A few bones were so fragile that they tended to crumble during surgery and in these patients cast immobilization was employed. Conclusions: Viability of bone is enhanced by minimizing the number of osteotomies and periosteal stripping. Oblique osteotomies provide sufficient rotational stability that post-operative immobilization is unnecessary.
The newer techniques of cementing aim to improve interlock between cement and bone around a femoral stem by combining high pressure and reduced viscosity. This may produce increased embolisation of fat and marrow leading to hypotension, impaired pulmonary gas exchange and death. For this reason the use of high pressures has been questioned. We compared finger-packing with the use of a cement gun by measuring intramedullary pressures during the cementing of 31 total hip replacements and measuring physiological changes in 19 patients. We also measured pressure in more detail in a laboratory model. In the clinical series the higher pressures were produced by using a gun, but this caused less physiological disturbance than finger-packing. The laboratory studies showed more consistent results with the gun technique, but for both methods of cementing the highest pressures were generated during the insertion of the stem of the prosthesis.
